


Pink and Blue

by VampyrePrince



Category: Undertale (Video Game)
Genre: F/F, F/M, Fluff and Smut, M/M, Robot Sex, heart core stimulation
Language: English
Status: In-Progress
Published: 2015-12-19
Updated: 2015-12-19
Packaged: 2018-05-07 14:12:25
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 4
Words: 4,447
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5459321
Author URL: https://archiveofourown.org/users/VampyrePrince/pseuds/VampyrePrince
Summary: <blockquote class="userstuff">
              <p>After coming to the surface, Mettaton finally realizes after a visit from Napstablook that he left the ghost on bad terms. Believing his old friend deserved a happy ending as well, he convinces Alphys to build a robot body for Napstablook. Mettaton then shows Blooky just how happy his ending can be.</p>
            </blockquote>





	1. Another Medium - Intro

**Author's Note:**

> Okay so, I've never written this kind of smut before, and at first I thought it would be strange to write about sex without certain body parts, but I then realized that robot heart core sex is pretty damn sexy too. Napstablook didn't seem to get much of a happy ending, so I wanted to give him one. *Hopefully you've gotten the house key from Bratty and Catty or there may be spoilers!*

"You should be, um, as good as new, Mettaton!" Alphys smiled happily as she wiped the sweat from her brow. Her finest invention sat cross legged on her work desk, marveling at his improved mobility and even more flexible arms.

"Beautiful work, darling. I feel like I could dance!" Mettaton hopped off the desk and stretched, posing before his creator who seemed just slightly flustered. At times she wished she'd never given him such an attractive appearance, because every time she had to do repairs she ended up in a horrible sweat - from what she wasn't sure, or rather she refused to admit. Either way, he was a great success with everyone from the Underground, and an even bigger hit on the Surface.

It was a wonderful place. The humans had taken time to come around, but with the help of Frisk and Asgore, and Sans to keep Papyrus from frightening them too much, peace seemed to finally exist among them. There were of course humans who disliked the monsters as would have been expected, but that was true for things even on the Surface before the monsters came to live aside them. It's just the way humans were, and continue to be. There would always be a group opposed to something, even if it were a good thing. Regardless of such disagreeable natures, the monsters remained Determined, finally finding a place within normal every day life. Everything was as it should be.

A ringing phone brought Alphys back to reality. She fumbled with the device before dropping it on her basement floor, slightly cracking the screen. "Oh, d-damn it! I'll have to repair this later!" She viewed the screen to see that the missed call was from Undyne, and she flew into another anxious fit, trying to dial back as quickly as possible over the crack. "E-excuse me!" Alphys stuttered to Mettaton as she ran upstairs to get a better signal, leaving the robot celebrity to himself.

"She needn't be shy." He giggled. "I've heard plenty of far more interesting things when they have sleepovers." He crossed his arms and looked about the room - boredom striking him with an unbearable feeling. "Maybe I'll check out that Youtube thing Alphys is always on."

"Uh, um, Met... Mettaton?"

Mettaton turned to see a sulking ghostly form floating through the wall. "Blooky! Long time no see."

"Yes, it has been." The ghost smiled weakly. "Did you... say Youtube?"

"Yes, Alphys has told me a bit about it. Seems like a good place for this gorgeous figure of mine to make an appearance." Mettaton flipped his hair for flourish, causing a light blue blush to light up Napstablook's form.

"I know about that site... I have music posted there..."

"Lovely!" Mettaton held out his arms. "Come here, Blooky! You're just who I need."

"Uh, um, I'll just... go through you..." Napstablook frowned and tears formed in his eyes. Mettaton came forward and hugged the ghost anyway, his heart core dimming slightly.

"You know I don't mind, Blooky, although I do miss the way we used to embrace."

"It's my fault we can't anymore... I'm not cool enough to be given a robot body like you were. You're so much cooler than me... Mettaton. I was always so boring and no one paid attention to me..."

"Shhhh, Blooky. Don't forget that I'm still the same ghost that I was before this fabulous makeover." Mettaton looked into Napstablook's lifeless eyes, smiling. "Do you remember living side by side in the Underground?"

"Yes..." Napstablook felt his mood lighten at the not so distant memory. "Your house was the pink one... beside my blue one."

"Yes. We were inseparable."

"But now we are separated, and it's all because I'm not cool enough to-" Napstablook became silent as Mettaton brushed his lips against the ghostly form's face.

"We are on the surface now. All of the time in the world is ours, darling." Mettaton backed away, clapping his hands together as he smiled. "And so, with that in mind, I will ask Alphys to make you a body like mine."

"O-oh no... That's too much trouble... oh no... I'll be a burden. Oh..." Napstablook's form shivered with his upset.

"Of course not, Blooky. If Alphys won't agree to make a body for you, then I'll do it myself." Mettaton shrugged. "How hard can it be?"

"Oh... I'm sorry. It's too much to ask. I'd better go now... Bye for now, Mettaton..."

"Blooky, wait!" Mettaton reached out to try to grasp his friend, but before the form disappeared he knew it was fruitless. A sadness washed over him as the memories came back; the memories of Blooky and him living side by side, two houses next to each other, one blue and one pink. He could still hear the distant musical remixes Napstablook would make through their thin walls, and recalled the exact moment that all of that ended. It was because of his own selfish desire to become a star that he abandoned Napstablook, the one closest to his ghost heart. Ever since they'd grown far apart, and Napstablook took on a more depressed, reserved personality. 

The ghost had always been a bit of a downer to begin with, but with his love for music and his ever growing love for his pink ghost companion he was happier then. Mettaton smiled sadly as he remembered the evenings (or was it days? It was difficult to tell in the Underground)when Blooky would play back a new haunting remix for Mettaton to sing to. It made being trapped beneath the Surface so much more bearable, although it seemed that the concept of night and day, and time itself, just seemed to not exist down there. Living in perpetual darkness with artificial lighting for years made it a wonder that they even adjusted well to the Surface at all, but that was a distant memory now – just as much as Team Blooky and Mettaton.

Suddenly losing his interest for internet fame, Mettaton sulked back into a corner and sat with his knees to his chest, his mind in a rare state of sadness. It was times like these that he couldn't bear to put on a show.


	2. Fallen Down into Napstachords

**Summary for the Chapter:**

> Alphys has finally finished a new body for Napstablook, but will he like it?

[*Four Weeks Later]  


Alphys sighed as she fell into her chair, her hands black with grime from working with metal for the better part of the day. She smiled shyly at Mettaton and Frisk, who were sitting patiently on the other side of the room. “W-well, is it good? I mean – do you think he'll like it?” 

Frisk followed Mettaton to the table as they both looked over the gray and blue metalwork. The child smiled brightly and gave Alphys a thumbs up, gaining a blush from the awkward scientist. “I like it! What do you think, Mettaton?”

“Hmmm, it could use some polishing, but otherwise it suits him well.” Mettaton picked up Frisk and nuzzled their nose playfully, hugging the child tightly in his happiness. “Finally! We've spent far too long being worlds apart – now he won't feel so left out!” Frisk giggled as they were embraced in a robot bear hug, pecking Mettaton lightly on the cheek. 

“I'm really happy for you, Mettaton! It must be sad to be without your friend for so long.” Frisk looked up at the robot as they were set on the floor, Metatton's expression shifting to one of guilt. 

“You shouldn't be happy for me, darling. For once this was not for me.” He looked to the table where Alphys had laid her cell phone, reaching over the child's head to pick it up. “I believe it's time,” then to Alphys, “don't you?”

“I really hope he likes this... Yes, i-it's time.”

*

Frisk squeezed Alphys' arm gently as Napstablook came floating through the lab. His form was shivering from nerves alone no doubt. His mood seemed to lighten as he laid eyes on Frisk, his form steadying slightly as he approached the table. “Um... you said there was a gift for me? Not that, um, I deserve a gift or anything...”

“On the table, Blooky.” Metaton crossed his arms and smiled, waiting for his friend's reaction. What happened was what he'd least expected, and he watched nervously as the ghost broke down into a fit of tears. “You're supposed to be happy, Blooky.”

“I... I a-am happy. At least, I think this is what happiness... feels like.” His tears began to curiously float upward as he looked over the robot body before him. “Oh no – but I must seem ungrateful. I... I am sorry. I do not deserve this...”

“Do you like it?” Alphys observed him carefully as she held Frisk in her lap so they could better see.

“Oh... Oh yes. I do like it!” Napstablook turned to Alphys as his tears faded. “How do I put it on? Or... get inside it?”

“Well, you see, I have to help you with that.” Alphys allowed Frisk to slide off her lap and approached Napstablook. “I-if you'll follow me, I can help you fuse together with this body, b-but only if you want to.”

“What if... what if I want to un-fuse?”

“Why would you want to do that?” Mettaton slowly began to spiral down, his nerves getting the better of him. He was impatient and at a loss as to why any ghost would question such a great thing. 

“Oh – um, I wouldn't. Sorry... I'm being a bother, aren't I? Let's go, Alphys.”

“Follow me.” Alphys gathered the equipment into a large box, wheeling it before her into a back room where Napstablook followed. Frisk looked up to see Metatton's worried face and took his hand. The robot looked down at the child and smiled sweetly. 

“What do you think, little one?”

“I think you are the best friend that anyone could ask for!”

“You're too sweet.” He rustled the child's hair. “And to think I was originally built to destroy you.” Frisk giggled in response as they gripped Mettaton's hand tighter, waiting with the robot star for Alphys and Napstablook to re-emerge. It brought back memories of the time that they first met the depressed ghost. It was shortly after they'd fallen into the Underground and the ghost had been lying on a bed of leaves. It had been the first time in a long while that anyone had been so kind to the sad ghost, and Frisk remembered it fondly as the beginning of many friends that they would eventually make. Seeing Napstablook smile at last would definitely be worth it – although they figured that Mettaton would have much more to gain from it than anyone else could. 

It seemed like forever until Alphys emerged from the back room blushing madly, her hands finally clean of the black grime that was caked on them before. “I-I'm not sure how he feels about it yet. It takes time to, um, adjust if you'll remember, Mettaton.” Alphys came close to stand by Frisk, taking the child's hand to move them away from Mettaton. It seemed she was anticipating a reaction of some sort. 

“Blooky?” Mettaton approached the middle of the room as the sound of metal footsteps approached the doorway. His worried expression shifted into something more like his old self again, and he found himself moving across the room to embrace the newly emerged Napstablook in his gray and blue metal glory.

“M-Mettaton!” If robots could blush Napstablook would have been glowing. His design resembled that of Mettaton's, but differing in color and build. He had short blonde hair instead of black and wore a similar slim figure, but his heart center was blue instead of pink and rested as an inset in his stomach behind some sort of glass instead of an outset sort of belt like Mettaton's. He didn't have the same fabulous pair of boots, but instead wore something more flat and becoming of himself. Overall, Napstablook looked as he should have long ago. 

“Oh Blooky, I'm so happy. Are you happy?”

“I... I think I am happy.” He brought his new arms up to wrap around Mettaton, finally embracing his friend back. “I can't seem to cry.”

“Robots don't cry, darling.” Mettaton hummed happily and nuzzled Napstablook's nose, completely forgetting that Alphys and Frisk were still in the room. It was then that the scientist pulled Frisk away, mumbling something about how 'children probably shouldn't see this,' and ran upstairs with the child, closing a door loudly in her haste. 

“So... so it's good?”

“This was for you, Blooky. My opinion doesn't matter.” He traced the robot's mouth with his fingers, biting his lip seductively. “Although I must say, you are very smooch-able.”

“Oh... that's right. I h-have those.” 

“I should teach you how to use them.” Mettaton inched closer until their lips were locked together, a blue glow growing brighter from between them. Napstablook's voice box reverberated with a low hum as he fell into the kiss, his heart core stirring with happiness. 

“M-Mettaton... I have always wanted to do that... with you.” He pulled away and looked upon his friend in a new light, shifting his hands and arms to run up the pink robot's back. “I had thought I would never... ever... get to hug you again.”

“I plan to do more than hug, darling. There are many wonderful things that you can experience now that a ghost could not.”

“I-I, um... what things?” Napstablook averted his gaze in embarrassment, knowing full well what his friend meant. As a ghost he had entertained those sorts of ideas, especially with Mettaton because they were very close. Being ghosts, however, they were limited in the ways that they could show their affections, and they had grown to love their cuddling and nuzzling. This was an entire new world though, and to think that he was now capable of doing other much more indecent things was enough to cause his system to grow hot. “Is it always this warm being a robot?”

“Your system is reacting to your emotions, love.” Mettaton ran a hand down the blue robot's chest, trailing it to where his heart core rested. He traced the shape of the heart there, watching it curiously as the glow began to pulsate. “Oh – you like that, do you?”

“Uh – um... What are you-?”

“This, right here, is the key to many pleasures, Blooky.” He giggled as he circled his finger around the center of the glowing heart. “Just be careful not to blow an important fuse your first time. That would be quite embarrassing to ask Alphys to fix.”

“It f-feels... strange.” The robot's hips rocked forward as the new sensations caressed his very soul. He felt something building within, an unbearable heat that was threatening to burst as Mettaton's fingers gently circled the pulsating blue heart. 

“What's this? You're leaking?” Mettaton grinned as a coarse blue liquid began to seep from beneath the glass heart. “Naughty Blooky.”

“I c-can't... help it.” A small moan escaped Napstablook's lips as he kissed Mettaton again, his core growing brighter. It was then that he froze, a bursting sensation going off inside him as blue goo leaked onto Mettaton's hand. 

“Intense, isn't it?” Mettaton slid his fingers across the mess leaking down Napstablook's stomach. “I've always dreamed of this, darling.”

“I had no idea that... that this sort of thing really existed.”

“Of course it does. Humans do it all the time. Well, in a different way.”

“I like, um, this way. With you.”

“Oh, Blooky...” 

Napstablook looked into Mettaton's eyes, a look of happiness shining behind them. It seemed that for the moment his depression had gone for a short while, and he had felt true pleasures that he had never known before. It was as if he had found heaven upon the Surface, and his soul was singing. “Mettaton?”

“What is it, darling?”

“I... I think I love you.”


	3. Bone Brothers Quiz Show

**Summary for the Chapter:**

> Mettaton's first ventures into Youtube: Quiz shows. (because we didn't see that coming)

“Oooohhh Yeesss! Welcome my lovelies to another episode! Today we will be doing a quiz show with none other than,” a dramatic drum roll, “the Bone Brothers!”

“Bone brothers?” Papyrus glanced at Sans, his words becoming drowned by the applause track that Alphys was controlling in the back of the room.

“Just let him have his moment, Pap.” Sans smiled as the robot bathed in a fountain of confetti before whipping out a stack of note cards. 

“Today's questions should provide a challenge for our contestants! But first, why don't you introduce yourselves to the audience?” Obnoxious game show music queued in the background at Alphys' touch. It was slightly delayed by the distraction of her girlfriend, Undyne, at her side. She had trouble focusing when the girl was around. 

“Well, okay then! I am the Great Papyrus! The much taller and more culinary inclined brother, may I also add.”

“You callin' me short? C'mon Pap, throw me a bone here.” The music stopped momentarily for a drum sting. “I'm Sans, the punny one.”

“Your puns are as vile as that odd quiche thing you always make!”

“You know I tickle your funny bone, bro.” Sans winked at the camera, eating up the limelight. Alphys triggered a laugh track.

“Enough introductions! Let's get this quiz show on the road, shall we?” Mettaton focused on the first question that seemed to be barely readable. The thing was practically chicken scratch. “Who can tell me the star of... of... Mew Mew...? Alphys!”

“Ah! Um, well – you see I-”

“These are all about anime!” Mettaton flipped through the cards. “There's nothing about me!” 

“Y-yes. Um, I have extensive knowledge o-on, um, anime... and I thought that...”

“You're a huge dork, Alphys!” Undyne laughed and grabbed Alphys to give her a noogie.

“Oh dear...” Mettaton sighed and straightened up once more. “Okay then, anime it is! Now, let's see... one I can read...” 

“Oh my.” Papyrus leaned low to whisper to Sans. “I don't know anything about anime!”

“Eh, it's just a bunch of big swords, busty women, and awkward moments.”

“I see.” 

“First legible question!” Mettaton pointed to the brothers with the note card. “What power does the main character of Mew Mew Kissy have?”

“I think we need a 'mew' question.” Alphys triggered another drum sting for Sans before Mettaton flipped to another card, finally turning to the back of the lab. 

“Oh, cut! Cut! This isn't working.” The music and sounds all stopped as Alphys powered down the mixer. Mettaton dropped the cards onto Alphys' desk and watched hopelessly as she darted her eyes about the room, her hands fumbling with each other. Undyne rubbed her head gently and kneeled down beside her girlfriend in an attempt to calm her anxiety. It brought a sudden spark to Mettaton's mind and he looked around the room, finding Napstablook in a corner with his headphones on. The guy never was much for flashy things, so it only offended him slightly that his boyfriend had been ignoring the show the entire time. “How can my greatness possibly shine through like this?”

“Hey, Mettaton?” Frisk was pulling on the robot's hand and looking up at him. It always warmed Mettaton's heart to see them.

“What is it, darling?”

“I want to be on your next show! We can make it awesome together, okay?” Frisk smiled as Mettaton lifted them up as he always did, nuzzling the child's nose. 

“Alright, little one. And I promise it won't be a cooking show.” They both giggled at the memory as the tension finally eased in the room. Papyrus and Sans had approached the two while they were busy being sappy.

“Hey, Mettaton. Me and Pap gotta get going. We promised Toriel we'd go to the beach today.”

“You promised, brother. I am only accompanying you so you don't do anything you'll regret!” Papyrus looked down at Sans, scolding him for some apparent event that had happened before. Sans shrugged.

“So I kissed Toriel the last time we hung out.” Mettaton and Frisk both gasped.

“You kissed Asgore's wife?!”

“EX wife!” Sans exhaled the words in his frustration, grabbing Papyrus by the arm as they turned to leave. He was glowing with a blue blush. Frisk smiled sadly.

“I was hoping that Asgore and Toriel would make up.”

“Not everyone can have a happy ending, little one.” Mettaton set Frisk on the floor and glanced over at Napstablook. “But those that do deserve it.”

“But... doesn't Asgore deserve a happy ending too?”

“Oh – later, darling. We'll talk about that some other time.” Mettaton brushed by Frisk to approach Napstablook in the corner. “Speaking of happy endings...” There was a seductive tone to Mettaton's words that brought Napstablook to attention, gazing back into his boyfriend's eyes.

“Oh – I'm sorry. I wasn't, um, ignoring you or anything... Oh no. I'm a bad boyfriend.” Napstablook frowned as his headphones slid down around his neck.

“You're a bad boy alright.” Mettaton held out his hand for Napstablook to grab, lifting him off the chair. “You... didn't miss anything, love. It seems no one can understand how important it is that I look good for the public!” 

“You look good all the time to me, Mettaton.” Napstablook's heart core glowed blue as he blushed inside, causing Mettaton to crumble to pieces. It wasn't fair that his boyfriend was so freaking cute all the time like that. He turned around quickly and dragged the blue robot behind him, shouting to Alphys as they climbed the stairs. 

“Bedroom occupied!” Frisk raised an eyebrow and looked at Alphys and Undyne who had broken into fits of giggles.

“Do robots need to sleep?”

“Oh hell, Frisk!” Undyne broke into laughter that rendered her speechless. Alphys turned red as she tried to think of an appropriate answer for the child.

“U-um, no. Robots don't require sleep... They, um-”

“Are doing weird things that robots do.” Undyne finished vaguely before Alphys could make the situation anymore awkward. Frisk was not old enough for that kind of talk, and it was better if they didn't know, or rather, it was better that no one knew what the robots were really up to.


	4. Pink and Blue

**Summary for the Chapter:**

> Mettaton really enjoys putting on a performance, even if it's just a show for one.

Napstablook's body bounced as he hit the mattress hard, Mettaton jumping on top of him before he had a chance to react. “Naughty Blooky, ignoring my show.” He whined like a child as the blue robot below him stared up at him nervously – Mettaton never having been so aggressive before. They had messed around a bit since Napstablook had gotten his new body the week before, but this was the first time that things seemed to be too real. 

“Isn't this... This is Alphys' room.”

“You are correct, darling.” Mettaton captured his boyfriend's lips instantly, his hand already wandering down the blue metal work. “For our next question: What is the most sensitive spot on a robot's body?”

“M-Mettaton...!” Napstablook arched his back as Mettaton's glove came off and his fingers traced the blue heart near his stomach.

“I'll give you a hint.” He pressed down on the small heart-shaped glass window and it popped open, revealing a glowing blue core.

“W-wait! Is it safe to open it?” 

“Safe? Oh, love.” Mettaton broke into giggles. “I would never do anything that wasn't.” He pressed two fingers into the soft but firm blue core, reveling in the moan that slipped out of Napstablook's mouth. “What we did before was merely foreplay.”

“This is... This is more intense!” 

“You still haven't answered the question.” Mettaton twisted his fingers into the blue core, watching curiously as his boyfriend arched his back again. It was beginning to leak down his side.

“I-it's... my core.”

“Correct, Blooky. Time for your reward.” Mettaton lifted his fingers and crawled down the bed, a mischievous smile playing on his face. Napstablook lifted himself up onto his elbows to watch what his boyfriend was doing, his insides growing hot again.

“You're not g-going to...!” The blue robot threw his head back as he felt Mettaton's tongue tease the edge of the heart-shaped core, the odd flexibility of a robot's tongue providing a much more erotic sensation than fingers. 

“Should I see how it tastes?” 

“We... we're r-robots. We c-can't-!”

“I'll use my imagination, darling.” Mettaton dipped his tongue into the glowing blue, swirling it around until he felt certain that Napstablook was going to blow a fuse. His boyfriend was rocking his hips and squirming above him, moaning louder than he'd dared to before. Mettaton felt his heart core already beginning to drip down his thighs as he traced the edge of the blue heart with his tongue again, rising to sit up over Napstablook's legs. A bit of blue dripped from his lip as he circled his pink core with his fingers, staring into Napstablook's enraptured gaze. “I want you to touch me this time. Can you do that?”

Napstablook sat up, taking Mettaton by surprise as he kissed his boyfriend hard, his own core leaking onto the bed sheets. His fingers were shaky as they found Mettaton's heart core. He carefully trailed the tips around the edge as Mettaton moaned into his mouth, and then quickly popped open the window to slip his fingers inside. Mettaton's hands slid into Napstablook's blonde hair, squeezing as he rocked his hips with the fingers twisting inside his pink core. “Oh, Blooky...! I want you to make me come!” 

“I-I don't know if-!” Mettaton interrupted his boyfriend's self doubt with a deep kiss, running his fingers back down to find Napstablook's blue heart. They both fell back onto the bed, Mettaton still over Napstablook as they dug within each others' cores. Pink dripped down onto blue as they neared their limits, their bodies reaching the peak point before that beautiful tiny explosion erupted within them. 

Mettaton groaned as he sat back up to look down at his boyfriend, giggling as he saw a mixture of blue and pink all over the metalwork – and Alphys' bed. “We made quite the mess. I do hope Alphys doesn't mind a change of sheets.”

“Oh no... Is she going to be angry?” Napstablook threw his arm over his eyes in embarrassment. 

“Of course not, Blooky. I suspect that it will only amuse her. I think she has a robot fetish.”

“Oh, but Undyne is a... a fish?”

“Something like that.” Mettaton climbed off of Napstablook and took the already soiled bed sheets to wipe the pink and blue from his body. “I've caught her watching interesting robot videos online.” Mettaton's eyes opened wide then, a glint shining within them. “Blooky! I've got it!”

“Mettaton, no!” Napstablook sat up quickly and grabbed the sheet from his boyfriend who was positively beaming. “We can't do that!”

“Can't we? Are you shy, darling?”


End file.
